I'm using the original I6 K member and a 'dropped' center link from an originally V8/273 equipped early "A" body. If that, for some reason, won't work, new, aftermarket pieces now exist.
None of that applies to me.
I'm using Schumacher's I6 to V8 motor mounts with my stock K member.
I dismembered a '73 Dart for all of the pertinent suspension and brake hardware. Everything but the aforementioned center link is '73 Dart.
Perhaps I should've included details on the K member and motor mounts but didn't think them pertinent at the time.